*{
    padding: 0;
    margin: 0;
}
.con{
    width: 1200px;
    margin: 0 auto;
}
.bn{
    width: 33.333333%;
    height: 100px;
    line-height: 100px;
    float: left;
    color: aqua;
    background: blueviolet;
}
.con:after{
    clear: both;
    display: table;
    content: "";
}
.bn{
    text-align: center;
}